# bit (1.1-10)

A class for vectors of 1-bit booleans.

http://ff.r-forge.r-project.org/

http://cran.r-project.org/web/packages/bit

bitmapped vectors of booleans (no NAs), coercion from and to logicals, integers and integer subscripts; fast boolean operators and fast summary statistics. With 'bit' vectors you can store true binary booleans {FALSE,TRUE} at the expense of 1 bit only, on a 32 bit architecture this means factor 32 less RAM and ~ factor 32 more speed on boolean operations. Due to overhead of R calls, actual speed gain depends on the size of the vector: expect gains for vectors of size > 10000 elements. Even for one-time boolean operations it can pay-off to convert to bit, the pay-off is obvious, when such components are used more than once. Reading from and writing to bit is approximately as fast as accessing standard logicals - mostly due to R's time for memory allocation. The package allows to work with pre-allocated memory for return values by calling .Call() directly: when evaluating the speed of C-access with pre-allocated vector memory, coping from bit to logical requires only 70% of the time for copying from logical to logical; and copying from logical to bit comes at a performance penalty of 150%. the package now contains further classes for representing logical selections: 'bitwhich' for very skewed selections and 'ri' for selecting ranges of values for chunked processing. All three index classes can be used for subsetting 'ff' objects (ff-2.1-0 and higher).

**Maintainer**:
Jens OehlschlĂ¤gel

**Author(s)**: Jens OehlschlĂ¤gel <Jens.Oehlschlaegel@truecluster.com>

**License**: GPL-2

**Uses**: Does not use any package

**Reverse depends**: bit64, eigendog, ff, ffbase, MSBVAR, NEff, tabplot, TOC

**Reverse suggests**: bamlss, checkmate, Stack, symDMatrix

Released about 7 years ago.